var x1 >=0 ;
var x2 >=0 ;
var x3 >=0 ;
var x4 >=0 ;
var x5 >=0 ;
var x6 >=0 ;
var x7 >=0 ;
maximize obj: 1.0  -1.0 * x2   + 2.0 * x4   + 3.0 * x5   + 1.0 * x7 ;
c1: x1 = 1.0  + 0.0 * x2  + 0.0 * x4  -1.0 * x5  -2.0 * x7 ;
c2: x3 = 3.0  + 1.0 * x2  -1.0 * x4  + 0.0 * x5  -1.0 * x7 ;
c3: x6 = 0.0  -1.0 * x2  + 0.0 * x4  -2.0 * x5  + 0.0 * x7 ;
solve; 
display 1.0  -1.0 * x2   + 2.0 * x4   + 3.0 * x5   + 1.0 * x7 ;
 
 end; 
